The present invention relates to an apparatus for switching or controlling cyclone separators. Cyclone separators are used, for example, in the crankcase ventilation of internal combustion engines. They serve to separate the crankcase gas from liquid components, such as oil mist. The crankcase gas is set into rotation inside the cyclone separator. The oil mist or oil droplets are deposited along the wall of the cyclone separator and flow back into an oil pan via a discharge pipe. The deoiled gas is conducted to the intake tract of the internal combustion engine via a pressure control valve and is returned to the intake air.
The amount of crankcase gas depends on the operating state of the engine and may range, for example, from 50 to 220 liters per minute. A cyclone separator has an optimal operating point at a specific gas amount. To reliably deoil the different amounts of gas, a plurality of switchable cyclones must be provided, which are switched on or off depending on the gas amount. Approaches to solve this problem are known, e.g., the use of additional valves to switch the cyclones on or off.
U.S. Pat. No. 6,684,864 (=DE 199 18 311) discloses a method for deoiling crankcase ventilation gases and an apparatus for carrying out this method. In this device, the volumetric flow of the crankcase gases is divided into at least two partial streams, and at least one partial stream is guided through at least one oil separating element. The size of the partial streams is regulated as a function of the magnitude of the volumetric flow.
U.S. Pat. No. 6,942,709 (=DE 102 05 981) discloses a system with switchable cyclones for separating particles or droplets from a fluid stream. At least two cyclones, which have a tangential inlet opening for the fluid stream, are connected in parallel. Each inlet opening for the fluid stream can be opened or closed individually. Controlling the fluid stream is very important for the optimal deoiling of crankcase gases because the optimal efficiency of the cyclones is limited to a very narrow operating range. Control of the volumetric flow must therefore be designed precisely for this optimal operating range. On the other hand, the system should be simple in construction and have little or no tendency to malfunction.